Process and apparatus for digesting or cooking fibrous material



1,633,734 June 1927' F. K. FISH, JR

PROCESS AND APPARATUS FOR DIGESTING 0R COOKING FIBROUS MATERIAL Original Filed Julyl4. 1925 VE TOR. HA (J 1 7 ATTORNEYS.

Patented June 28, 1927.-

. YUNITED STATES P T nT-oFr cn;

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PEQCESS AND APPARATUS FOR DIGESTINGOR COOKING FIBROUS MAZIERIAL,

A lication lna July 14,1935, Serial m. 43,597. Renewed May 24, nm.

This invention relatew to a process and apparatus for digesting or cooking fibrous |ll:ll ('l'l1ll and more mrtrcularly to the cuculalion oithe cooking liquor used in the twalnu-ut of the fibrous material in the manufacture of pulp.

Such materials are now treated with various cooking liquors for the purpose of removing the substances which cncrust the lihrc in a manner well known in the art, and in processes known to me much time is mnsumed in the arcumplishuu-nt of the desired result. I'haverouud that. the most ell'cctive application of the rookiu; liquor is obtained 1 by circulating the liquor. or in other words keeping it in motion, which causes a mixing of. the reagent employed and the extractives liberated from the n'uiterinl being treated, which reduces the period of the cook and material! improves the product. It is thus an Ol'JjGCh of thisinvention to provide u process and apparatus: in which the eookingliquor is brought into contact with the material under treatment in an effective manner .in order to make full use ,of the digesting properties of the liquor in the cook.

. A furtherohject of the invention is the provision of a process and apparatus for regulating the temperature of the digesting liquor without the addition of cxcosq steam to the digestcr or exposing the liquor to the atmosphere.

Another object of the invention is the provision of a simple process and apparatus for circulating the liquor and causing it. to etlectively'enter the material being treated.

The objects and ad antages will appear from the detailed description in the specification and will be particularly pointed out in the claims.

For a clear understanding of the ll'lVOll-- lion, reference is made to the accompanying drawing. which illustrates one form of apparatus for carrying out the rocess.

In tho driuviugs 1 illustrates a digcuteu screen '(not shown) n'iatcrial frompnlcrinu. the pipe :3 and-tho pipe 7 is provided with a. perforated nozzle 9. A. further pipe. ltl haring a' ralrc. ll connects the hcntrr with the topporlion of the digester above the lcvrl ol the charlie therein.

in tho (oohing of such mall-rials it is very lmn of liquor in the holder hand then forcin; it into th'r lower ronirnl portionpf tho divc tcr in a tangential mum-10mm" pnrtol' the liquor may l'l(|'(llll'l1(tl to lllQttl') oli'l'hc dig-outer through the pipe 10.

This lrcalnu'ut not only' raises the trampcraluro ol' the cooking liquor hut causcn'fu circulation and agitation within the charge of material which lu'ings tho hcalcd liquor circulation and-agitation of the liguor and charge tends to hasten the cook an to give more uniform results throughout the entire charge. in arldmom the -tempcrnturc is raised as desired without. undue dilution of th treating liquor.

Moreover. l lmro f und that an effective ,l-irrulntimi of liquor may he oll'cctcd in the rligestor. without the use of the pump. When the liquor flows into the heater its temperature is quickly raised and this rise prcrrnts the li' 'hrouis hmtom of tho dignslm by means" of tho pump 4. raising: the'tcmpcrn'ture of this pol"! into the conicnl portion of the digester in temperature causes the liquor to flow through the outlet of the heater to the dicester. thus causing circulation of the liquor as well as securing the required temperature without dilution of the liquor.

cient, liquor will be Furthermore, b closing the valves 8 and 11 without era ing the pump, the heater will become lled with H uor and when the pressure in the heater I IG,-t0 the rise intemperature of the li uon therein, is sufiiiorced back into the bottom of the digestcr with"the result of keeping the liquor, consequently the-material being treated, in movement, which greatly assists in causing thorough mixing of the retained gases and solvents with the extractives 1 liberated from the material under treatment.

I claim: Y l: A processof digesting fibrous material which consists in treating the material with a cooking liquor in a digester, withdrawing a portion of the liquor from the bottom of the digcstor, raising the temperature of the withdrawn portion of-liquor and returning it-to the lower conical part=of the digester,

and there releasing it in ,a manner to cause agitation without any substantial compactr 8. A proc'ess as defined inclaim 2 wherein the heated withdrawn portion of liquor is given a swirling u ward circulation in the ottom portion of t 1e digester.

4. In'a process of digesting fibrous material cireulating'cooking li nor from the bottom of the digestcr throng a heater and back to: the lower part of the-digester to cause a movement of the liquor andzmaterial immersed therein in order to hasten the cook, the circulation being mch as to affect substantially the whole charge.

5.,Ina process of digestingifibrous material the step which consists in producing in the lower conical portion of the digester a swirling movement of the liquor.

6. Ina process of digesting fibrous material in a .di ester the-steps which consist in permitting iquor to flow from the bottom of'thedigester to a heater and rapidly raising the temperature of the liquor in the heater to create pressure therein to force the heated liquor back-to the bottom of the cligester.

7. An apparatus for digesting fibrous matori-a1 which consists of a' digester, a pump connected to the lower end of the digester,

a heater connected to the discharge end 0!; i

the said pump and a pipe connecting said heater to. the lower conical portion-of the digester in a tangential manner.

8. An apparatus for digesting fibrous 'material having in combination a digester and a heater, so connected to the digester new be adapted to cause a circulation of liquor from the bottom of the digester'back to the lower conical portion of the digester in a tangential manner. I

. 9. A digester for cooking. fibrous material having in combination means for admitting fluid to the lower conical portion of the said digester, said means being connected. to the digester in a. tangential manner.-

- 10. An apparatus as defined in claim 9;

having means for-circulating a portion of; the, heated liquor to the top of the digester substantially as described In testimony whereof I allix mysignature.

FREDERICK K. FISH J a. 

